1. Field of the Invention
The present invention relates to a method for detecting leaks in the wall of a test object, container or similar, by measuring and evaluating changes that occur in a partial gas pressure and a method for localizing the detected leak as well as devices for implementing said method.
2. Technical Background
It is known to search and, if required, determine leaks with the aid of test gases, preferably helium. To this end, the wall, which is to be analyzed for the presence of leaks, is exposed to a differential pressure. The partial pressure of the test gas is increased on the side at the higher pressure. If a leak is present, test gas will penetrate. On the side at the lower pressure, there is present a test gas leakage detector, commonly a mass spectrometer, which records the rise in the partial pressure of the test gas.
Mass spectrometers are relatively expensive and sensitive. They may only be operated at pressures of about 10−4 mbar or lower. The use of mass spectrometers necessitates, for this reason, an engineering- and financially-wise relatively high investment.
It is the task of the present invention to propose methods of the aforementioned kind as well as devices suited for implementing these methods in which the engineering- and financially-wise investment is reduced.
This task is solved by the present invention through the characteristic features of the patent claims.
The employment of oxygen as the test gas permits the use of oxygen sensors as the test gas detector. Preferably solid electrolyte O2 sensors are employed. These are being employed for some time now, for example, in monitoring the exhaust gas discharged from the catalytic converters of vehicles. These sensors do not require a high vacuum to operate. When being implemented by way of a micro design they are linear over wide ranges, and above all sufficiently sensitive so that leakage detection according to the present invention can be performed at a sensitivity level comparable to that of helium leakage detection. The employment of oxygen as the test gas offers the additional advantage, that the user of this leakage detection method is informed specifically about the presence of this gas, namely O2, which is of special importance in many applications.
Further benefits and details of the present invention shall be explained with reference to the examples of embodiments depicted in drawing FIGS. 1 to 4 and the methods described with reference to these.